The first Wikimania was held in August 2005, in Frankfurt, Germany. It was conceived of as the first international conference of the Wikimedia Foundation, and a chance for members from all the various projects and communities to meet. It had grown from an idea into a certainty the previous summer, at which point a discussion and vote was held on Meta regarding where in the world such an event should be held, leading to a final city selection in late October. There was talk about whether to make the conference an annual affair.

Frankfurt am Main was chosen as the host city. One of the advantages of holding it there was the promise of a venue other than a hotel which could offer both housing and conference halls. This was the Haus der Jugend, a youth hostel and conference center in Frankfurt's old city.

Wikimania included a session of hacking days and a main conference; together, these took over the Haus der Jugend for a week. Breakfasts and lunches were group affairs in the hostel's cafeteria, and a party Saturday night left everyone in high spirits. Ten conference speakers and attendees from around the world had their attendance sponsored by the Open Society Institute; they arrived early in the week, and stayed through the end of the conference. Other conference sponsors included Socialtext, Answers.com, DocCheck, Gruppo Logos, and Sun Microsystems, which sponsored the party.

Hacking days ran from Monday to Thursday, and involved a growing number of developers as the week passed. Each day saw a few long discussions on a particular theme related to Wikimedia servers or MediaWiki development. By Thursday, when hacking days ended at lunch, there were some 30 people present.

The main conference ran for three days, drawing speakers from industry and Wikimedians from 51 countries. Almost 400 people came to part of the event; on the busiest day, there were 300 in attendance at one time. The local and national media loved the conference; over 100 of them came to part of the conference as well. The Haus der Jugend was festive, and host also to a few other groups during this week. It had a large lounge and patios open all night. They were good-natured about being overrun by Wikimaniacs, and allowed a small building in their courtyard to be used throughout the week as an organization center.